Tubular article manufacture



Oct. 25, 1938.

G. s. MCLAYI 2,134520 TUBULAR ARTICLE MANUFACTURE Filed March 24, 1957 Patented Oct. 25, 1938 PATENT OFFICE 2,134,620 TUBULAR ARTICLE MANUFACTURE 1 Gavin Smellie McLay, Strand, London, England,

assignor to Wcllman Seaver Rolling MillCompany Limited, London, England, a company of Great Britain I Application March 24, 1937, Serial No. 132,829

- 1 In Great Britain July 30, 1936 Claims. (o1. 205-4) This inventionrelates to a method of and apparatus for the manufacture of metal'tubes and other tubular metal articles hereinafter called tubes. g

The apparatus is of the push bench type by p which a somewhat thick cup-shaped hollow billet or blank, usually termed a bottle, carried on an end of a mandrel is pushed through reducing means, such as dies, or through passes between rolls which decrease successively in cross-sectional area in the forward direction, whereby the billet is reduced in thickness and spread out lengthwise along the mandrel until the billet is brought to or approximately to the form of a tube of the required thickness and length. An example of such apparatus is'described in the specification of U. S. Letters Patent-No. 1,979,579.

In a usual method of operation of such apparatus', the mandrel is removed from the apparatus, the tube stripped therefrom and the mandrel returned tothe'apparatus with the same end at the front for use in the production of a further tube. comes non-uniformly heated which causes changes of shape resulting in uneven wear of the mandrel and lack of uniformity in successive tubes produced. It is an object of the'present invention to overcome these difficulties.

It has been proposed in the'operation of push bench drawing apparatus (see the specification of U. S. Letters Pa'tent No. 2,098,153) to reverse the mandrel end for end after the formation and removal of a tube and before it is used'for the production of a second tube.

Mandrels which are to be reversed should have their ends similar so that either end can be engaged by the mandrel carrier which operates on the mandrel tomove it forward. A mandrel to be reversed has been proposed having both ends similar and with each end formed slightly rounded or convex to co-operate with a mandrel carrier having its end hollow or concave of corresponding shape to engage the end of the mandrel. It has been found that such shaping of the end of the mandrel and mandrel carrier is unsatisfactory in that under the shocks experienced during the pushing operation and particularly the shock produced when the bottle meets the first die, the end of the mandrel becomes disengaged from the mandrel carrier with the result that its alignment may become incorrect and also when the mandrel carrier catches up and again engages the mandrel the engagement is not correct. The tube produced is then imperfect and not true.

Itis also an objectof the present inventionto' It is found that the mandrel beovercome this difficulty and to provide a mandrel which may be reversed and which will at all times be maintained in engagement and correct alignment with the mandrel carrier during the pushing operation whatever shocks may be pro- 5 duced during that operation.

Experiment has shown that this purpose may be satisfactorily effected by shaping the co-operating ends of the mandrel and mandrel carrier so that the one has, for example, a conical extension of less diameter at its base than the diameter of the mandrel and the other has a corresponding depression to receive said extension, the mandrel being shaped similarly at its two ends and having no depressions or grooves in its cylindrical face.

The present invention comprises a method of producing metal tubes in which a closed ended hollow blank is applied to one end of a mandrel having its cylindrical surface plain without depressions or grooves and its opposite ends alike and whose other end is connected to the mandrel carrier by a connection which maintains said mandrel carrier and mandrel coaxial and which is not broken when the mandrel is subjected to shocks during the pushing operation, pushing the blank carried on the mandrel through reducing means to convert it to a tubular article, removing said tubular article from the mandrel, reversing the mandrel end for end and reintroducing it into the push bench apparatus for use in the production of a further tubular article.

According to the invention also apparatus for the production of metal tubes comprises in combination, a mandrel carrier, a mandrel having its cylindrical surface plain without depressions or grooves and its opposite ends alike, a connection between the front end of the mandrel carrier and the adjacent end of the mandrel which maintains the mandrel carrier and mandrel coaxial and which is not broken when the mandrel is subjected to shocks during the pushing operation, driving means for the mandrel, stripping means to remove a tube from the mandrel and means to receive the mandrel and reverse it end for end prior to reintroducing it in front of the mandrel carrier.

Further according to the invention a mandrel for use with push bench apparatus has its cylindrical wall plain without depressions or grooves, and its ends shaped alike, each with a conical extension or a conical depression of less diameter at its base than the diameter of the mandrel and of such length that it will. not be disengaged from a corresponding andsimilar hollow in or 55 extension on the end of the mandrel carrier when subjected to shocks during the pushing operation.

The means to receive the mandrel and reverse it end for end may comprise a turntable which operates in a horizontal or a vertical plane.

One form of push bench plant embodying the features of the present invention and its operation will now be described by way of example with reference to the accompanying drawing,

wherein- Fig. 1 shows a diagrammatic plan of the layout of the apparatus, and

Fig. 2 shows to an enlarged scale the connection between the mandrel carrier and the mandrel and the other end of the mandrel forced into the metal of the bottle after it has met the first part of the reducing means.

Fig. 3 is a fragmentary view showing an alternative form of the connection.

The plant comprises a push bench apparatus having a driving rack I, a mandrel carrier 2, a mandrel 3, and dies 4 which decrease successively in cross-sectional area and which are mounted in a ring bed 5 and, if desired, a reeling mill 6 of a known form and arranged in line. I is the hollow billet or bottle and 8 is the tube formed on the mandrel 3. The mandrel 3 is a cylindrical steel bar with its cylindrical face plain without grooves or depressions. In Fig. 2, each end is formed with a conical extension 9 whose base has a diameter less than that of the mandrel. The junction of the conical wall with the end wall is preferably rounded as is the end ID of the extension.

The front end of the mandrel carrier has a conical depression H into which the conical extension 9 of the mandrel is received. The length of the extension 9 is such that it will not become disengaged from the mandrel carrier when subjected to the shocks experienced in the pushing operation. As an example for producing a tube of 4.5 inches diameter at a pushing speed of 300. feet per minute the length of the extension may be 2 inches. The two ends of the mandrel are exactly similar, each having a conical extension 9.

In use on meeting the first die the bottle 1 is forced on to the mandrel 3 so that the conical extension 9 is forced into the metal of the end Wall of the bottle 1 as indicated in Fig. 2.

After the mandrel with the tube on it has passed through the reeling mill 6 by which the tube is loosened on the mandrel it is delivered to a skid table I2 by which it is delivered to stripping apparatus. The stripping apparatus illustrated comprises a pair of gripping jaws l-3 which engage the mandrel and hold it while a slotted plate M placed at the back of the tube 8 and attached by rods l5 to hydraulic apparatus I6 is drawn back by the latter to remove the tube from the mandrel. From the grippers l3 the mandrel is delivered to a roller conveyor table II which comprises a series of driven rollers I8 and is arranged in line with a turntable IS. The turntable is divided longitudinally so that the roller conveyor table I! delivers the mandrel to one side of said turntable.

The turntable l9 conveniently consists of a long frame structure 20 and it is of a Width to receive a desired number of mandrels on each side of the central division, for example 3. It carries on its underside rollers which run on a circular path carried on a frame, so that it may easily be rotated by any usual driving mechanism, and if desired it may be provided with means to raise it vertically prior to its rotation. The frame structure 20 is associated with two sets of driven rollers 2| which assist in delivering the mandrels to and from it. The turntable may be operated manually or may be power driven. The other side of the turntable I9 is in line with a second roller conveyor table 22 consisting of a series of driven rollers 23. The mandrels which have been turned round end for end by the turntable l9 are delivered by the roller conveyor table 22 to a point opposite to a skid table 24 by which they may be delivered as required to the push bench apparatus. The roller table 22 is disposed opposite to a furnace 25 into which the mandrels may be fed. The furnace has a sloping floor so that the mandrels delivered to it travel across it from one side 26 to the other 21. It is provided at the discharge side with a pushing rod 28 to push a mandrel from the furnace and deliver it to the skid table 24 by which it is delivered tothe push bench apparatus.

Treating the mandrels in the furnace prior to their being reintroduced into the push bench apparatus assists in restoring the condition of the metal which may have changed due to uneven heating caused during the operation of the of the push bench apparatus.

It will be understood that various modifications can be made without departing from the invention, for example, the turntable may be arranged to operate in a vertical plane.

In use the mandrels are fed to one side of the turntable at the same time that mandrels are removed from the other side, and preferably they are reversed by the turntable in groups or batches of several together so that they are returned to the push bench apparatus at the same rate as they are received from it.

To remove a tube from a mandrel the tube may be held stationary and the mandrel withdrawn forwardly from it.

The ends of the mandrel being exactly similar either is successively engaged with the front end of' the mandrel carrier and the connection is such that the mandrel is not disengaged from the mandrel carrier when subjected to the shocks received during the pushing operation.

In the alternative arrangement illustrated in Fig. 3, each end of the mandrel 3 is formed with a conical depression I l the extension 9 being provided on the mandrel carrier 2. This arrangement has advantages similar to those set forth above.

What I claim is:

1. A method of producing metal tubes in which a closed ended hollow blank is applied to one end of a mandrel having its cylindrical surface plain without depressions or grooves and having its opposite ends alike and whose other end is connected to the mandrel carrier by a connection which maintains said mandrel carrier and mandrel coaxial and which is not broken when the mandrel is subjected to shocks during the pushing operation, pushing the blank carried on the mandrel'through reducing means to convert it to a tubular article, removing said tubu-' lar article from the mandrel, reversing the mandrel end for end and reintroducing it into the push bench apparatus for use in the production of a further tubular article.

2. A method of producing metal tubes in which a closed endedhollow blank is applied to one end of a mandrel having its cylindrical surface plain without depressions or -g-rooves,and having its which comprises a conical projection on one which is received into a similar shaped depression in the other, pushing the blankcarried on the mandrel through reducing means to convert it to a tubular article, removing said tubular article from thee mandrel, reversing the mandrel end for end and reintroducing it into the push bench apparatus for use in the production of a further tubular article.

3. A method of producing metal tubes in which a closed ended hollow blank is applied to one end of a mandrel having its cylindricalsurface plain without depressions or grooves and having its opposite ends alike and whose other end is connected to the mandrel carrier by a connection which comprises a conical projection on one which is received into a similar shaped depres sion in the other, said projection being of less diameter at its base than the diameter of the mandrel and of such length that it will not be disengaged from the depression which receives it when subjected-to shocks during the pushing operation, pushing the blank carried on the mandrel through reducing means to convert it to a tubular article, removing said tubular article from the mandrel, reversing the mandrel end for end and reintroducing it into the push bench apparatus for use in the production of a further tubular article.

4. A method of producing metal tubes in which a closed ended hollow blank is applied to one end of a mandrel having its cylindrical surface plain without depressions or grooves and having its opposite. ends alikeand whose other end is connected to the mandrel carrier by a connection which comprises a conical projection on one which-is received into a similar shaped depression in the other, said projection being of less diameter at its base than the diameter of the mandrel and of such length that it will not be disengaged from the depression which receives it when subjected to shocks during the pushing operation, pushing the blank carried on the mandrel through reducing means to convert it to a tubular article, removing said tubular article from the mandrel, reversing the mandrel end for 'end and reintroducing it into the push bench ap paratus for use in the production of a further tubular article, and submitting the mandrel to a heat treatment before it is reintroduced into the push bench apparatus.

5. Apparatus for the production of metal tubes comprising in combination, a mandrel carrier, a mandrel having its cylindrical surface plain without depressions or grooves and its opposite ends alike, a connection between the front end of the mandrel carrier and the adjacent end of the mandrel which maintains the mandrel carrier and mandrel coaxial and which is not broken when the mandrel is subjected to shocks during the pushing operation, driving means for the mandrel, stripping meansto remove a tube fromthe mandrel and means to receive the mandrel and reverse it end for end prior to reintroducing it in front of the mandrel carrier.

6. Apparatus for the production of metal tubes comprising in combination a mandrel carrier element, a mandrel element having its cylindrical surface plain without depressions or grooves and its opposite ends alike, a connection comprising a conical extension on one of the said elements received into a conical depression in the other of the said elements, which extension at its base is of less diameter than the diameter of the mandrel and is of such length that it will not be disengaged from the. conical depression when the mandrel is subjected to shocks during the pushing operation, driving means for the mandrel, stripping means to remove a tube from the mandrel, and means toreceive the mandrel and reverse it end for end prior to reintroducing it in front of the mandrel carrier.

'7. Apparatus for the. production of metal tubes comprising in combination a mandrel carrier element, a mandrel element having its cylindrical surface plain without depressions or grooves and itslopposi'te ends alike, a connection comprising a conical extension on one of the said elements received in a conical depression in the other operation, driving means for the mandrel, stripping means to remove a tube from the mandrel, means to receive the mandrel and reverse it end for end prior to reintroducing it in front of the mandrel carrier, and furnace apparatus for the heat treatment of a mandrel before it is reintroduced into the push bench apparatus.

8. Apparatus according to claim 6 wherein the junction of the conical extension with the wall of the element on which it is formed, is rounded and the end of the extension is also rounded.

9. A mandrel for use withpush bench apparatus having its cylindrical wall plain without depressions or grooves, and its ends shaped alike, each with a conical extension or a conical depression of less diameter at its base than the diameter of the mandrel and of such length that it will not be disengaged from a corresponding and similar hollow in or extension on the end of the mandrel carrier when subjected to shocks during the pushing operation.

10. A mandrel according to claim 9, having a rounded junction of the conical extension or depression with the end wall of the mandrel and a 

